The present invention relates to an elastic crawler shoe suitable for use in a tracklaying vehicle such as a construction machine, an agricultural machine or the like.
In a conventional tracklaying vehicle such as a bulldozer, a crawler belt made of iron is wound around a plurality of rolling wheels arranged on the upper and lower parts of a track frame and is driven by driven drive sprockets so as to make the vehicle travel. However, a vehicle equipped with such an iron crawler belt damages the surface of a paved public road during traveling. For this reason, recently, what is called a rubber crawler belt system in which many core bars made of metal are embedded in an endless rubber belt at regular intervals and are engaged with the drive sprockets, thereby to drive the belt is often adopted.
However, in the case of this rubber crawler belt, since many core bars are embedded in the endless rubber belt, when the rubber belt is damaged resulting from cracks, exfoliation and the others, the rubber crawler belt as a whole needs to be replaced with a new one, and therefore there were problems that running costs on a user side run up and that time-consuming maintenance is required.
To overcome the foregoing problems, a crawler belt formed in such a manner that many elastic crawler shoes, each of which is comprised of one core bar and an elastic body bonded to the core bar so as to cover the core bar, are arranged in a longitudinal direction of a crawler is proposed, for instance, in Japanese Patent Laid-Open Publication No. 8-48269 (1996), International Publication No. WO99/12799 and the others. In the case of this proposed elastic crawler shoe, even when the elastic body in one of the elastic crawler shoes is damaged, only the damaged shoe can be replaced, and therefore this elastic crawler shoe is advantageous in that running costs and time required for maintenance can be cut down.
However, the above-mentioned known elastic crawler shoe has no particular twist added to a ground contact face of the elastic body since the shoe is designed on the assumption that it is used in all seasons and is therefore problematic in that when used, for example, on an icy road or a pressed snow road in winter, it cannot secure sufficient ground contact pressure, thereby causing a side skid due to a water membrane forming between the elastic body and the ground.
The present invention addresses the problem discussed above, and aims to provide an elastic crawler shoe capable of securing desired ground contact pressure on an icy road and a pressed snow road, thereby preventing a skid, and improving traveling stability and tractive performance of a tracklaying vehicle.
The above object can be achieved by an elastic crawler shoe according to a first aspect of the invention, the elastic crawler shoe comprising a core bar fixed directly or through an iron shoe to crawler belt links, each of which is endlessly coupled, and an elastic body bonded to the core bar so as to cover the core bar,
wherein the elastic body has a ground contact face having grooves or incisions.
According to the first aspect of the invention, in the elastic crawler shoe, the ground contact face of the elastic body has the grooves or the incisions, and therefore when the elastic crawler shoe is used on an icy road or a pressed snow road, edges of each of the grooves or the incisions scrape off a water membrane forming on the ice, and the thus-scraped water is stored in the groove or the incision. The removal of water membrane from the icy road or the pressed snow road thus increases gripping force of the elastic body relative to the road surface, thereby enhancing an anti-skid effect. As a result, traveling stability and tractive performance of a tracklaying vehicle can be improved.
An elastic crawler shoe according to a second aspect of the invention meets the first aspect of the invention and is further characterized in that in cases where the elastic body has the grooves, the grooves in the end portions in a longitudinal direction of the elastic crawler shoe are longer in length than the grooves in the central portion thereof. Thus, a ground contact area of the elastic body is secured in the central portion where ground contact pressure is relatively high, and in the elastic body, occurrence of cracks which start from the grooves in the central portion can be prevented.
An elastic crawler shoe according to a third aspect of the invention meets the first and second aspects of the invention and is further characterized in that the bottom of at least one of the grooves is provided with a wear indicator indicative of a wear limit of the elastic body. The wear limit of the elastic body, that is, a limit beyond which the anti-skid effect cannot be obtained is thus understood and is therefore effective in confirming right timing for replacement of the crawler shoe at a glance. In cases where a central ground contact face in the longitudinal direction of the crawler shoe is protrusively stepped, the wear indicator is so formed that its top face is flush with the end portions in the longitudinal direction of the crawler shoe.
An elastic crawler shoe according to a fourth aspect of the invention meets the first aspect of the invention and is further characterized in that in cases where the elastic body has the incisions, the central portion in the longitudinal direction of the elastic crawler shoe is more densely provided with the incisions than the end portions thereof. The incisions are inferior to the grooves in capacity for storing water scraped off from the icy road or the pressed snow road, and therefore in order to increase water membrane removing ability of the central portion where ground contact pressure is high, the central portion is effectively, more densely provided with the incisions.
An elastic crawler shoe according to a fifth aspect of the invention comprises a core bar fixed directly or through an iron shoe to crawler belt links, each of which is endlessly coupled, and an elastic body bonded to the core bar so as to cover the core bar,
wherein a central ground contact face in a longitudinal direction of the elastic crawler shoe is provided with stepped parts relative to end portions thereof so that the central ground contact face and the stepped parts can take the form of a convexity.
According to the fifth aspect of the invention, the stepped parts and the central ground contact face in the longitudinal direction of the elastic crawler shoe take the form of a convexity relative to the end portions thereof, and therefore when the elastic crawler shoe is used on the icy road, imposed load can be concentrated on the central portion in the longitudinal direction of the crawler shoe, thereby increasing ground contact pressure in the central portion and gripping force of the elastic body relative to the road surface. On the other hand, when the elastic crawler shoe is used on a snowy road, the elastic body engages the ground with its entire face including the central ground contact face, the stepped parts and the end portions, so that a ground contact area can be secured, and increased gripping force relative to the snowy road can be obtained. In this manner, desired effects can be obtained on both the icy road and the snowy road.
An elastic crawler shoe according to a sixth aspect of the invention meets the fifth aspect of the invention and is further characterized in that the stepped parts each have grooves or incisions oriented in a direction transverse to the longitudinal direction of the elastic crawler shoe. Thus, the edges of each of the grooves or the incisions provided in each of the stepped parts each assume a gripping function with respect to the icy road, so that an effect of preventing a side skid and the like can be enhanced.
An elastic crawler shoe according to a seventh aspect of the invention meets the fifth and sixth aspects of the invention and is further characterized in that a starting point of each of the stepped parts is provided so as to be in alignment with or deviate outwardly from each end of a flat part of the core bar. Thus, the elastic body""s stepped-downward part which has a great influence on ground contact pressure can substantially be in alignment with a portion of the elastic body, the portion corresponding to the core bar""s flat part where ground contact pressure is high, so that ground contact pressure relative to the icy road in particular increases, thereby increasing gripping force.
An elastic crawler shoe according to an eighth aspect of the invention comprises a core bar fixed directly or through an iron shoe to crawler belt links, each of which is endlessly coupled, and an elastic body bonded to the core bar so as to cover the core bar,
wherein a central ground contact face in a longitudinal direction of the elastic crawler shoe is formed out of a material harder than a material used for formation of end portions thereof.
According to the eighth aspect of the invention, the central ground contact face of the crawler shoe is formed out of a hard material, and therefore the central portion in the longitudinal direction of the crawler shoe can bite well into the icy road to exert a spike effect, thereby providing increased gripping force relative to the icy road.
An elastic crawler shoe according to a ninth aspect of the invention comprises a core bar fixed directly or through an iron shoe to crawler belt links, each of which is endlessly coupled, and an elastic body bonded to the core bar so as to cover the core bar,
wherein the elastic body has a laminated structure so that its ground contact face side portion can be formed out of a soft material while its core bar side portion can be formed out of a hard material.
According to the ninth aspect of the invention, the ground contact face side portion of the elastic body is formed out of a soft material, and therefore its adhesive effect with respect to the icy road causes gripping force, thereby preventing a skid relative to the road surface. On the other hand, the core bar side portion is formed out of a hard material, and therefore reduced ground contact pressure relative to the snowy road can be obtained.
An elastic crawler shoe according to a tenth aspect of the invention comprises a core bar fixed directly or through an iron shoe to crawler belt links, each of which is endlessly coupled, and an elastic body bonded to the core bar so as to cover the core bar,
wherein the elastic body is so formed that its ground contact area gradually reduces from the central portion in a longitudinal direction of the elastic crawler shoe toward the end portions thereof, and a slant face in each section orthogonal to the longitudinal direction of the elastic crawler shoe is formed into a circular arc.
According to the tenth aspect of the invention, the ground contact area of the elastic body gradually reduces from the central portion in the longitudinal direction of the elastic crawler shoe toward the end portions thereof, and therefore when the elastic crawler shoe is used on the pressed snow road, the increased amount of snow can be held between the adjacent elastic crawler shoes, so that increased gripping force relative to the road surface can be obtained. Moreover, since the slant face in each section orthogonal to the longitudinal direction of the elastic body is formed into a circular arc, when used on the icy road, an edge portion of each of the slant faces can be held nearly at right angles to the ground contact face of the elastic body and therefore bites well into the road, thereby increasing gripping force relative to the road surface.